The human heart is hollow muscular organ having four pumping chambers separated by four heart valves. The mitral and tricuspid valves, present at the left and right atrio-ventricular junctions, open and close in response to a pressure gradient during each cardiac cycle of relaxation and contraction to control the flow of blood to a particular region of the heart
These valves are comprised of a dense fibrous ring known as the annulus, leaflets or cusps attached to the annulus, and a complex of chordae tendineae and papillary muscles securing the leaflets. The size of the leaflets or cusps is such that when the heart contracts the resulting increased blood pressure formed within the ventricular cavity forces the leaflets towards the arterial cavity. As a result, the leaflets or cusps come in apposition to each other thereby closing the atrio-ventricular passage.
Natural defects and heart disease are common causes of valvular dysfunction within the heart of a patient. One common example of valvular dysfunction occurs when the annulus becomes excessively dilated or the valve geometry results in ineffective valve closure, which results in regurgitation. Due to the increased diameter of the annulus, the leaflets or cusps fail to meet during systolic contraction, thereby resulting in the regurgitation of blood during ventricular contractions. As such, sufficient back pressure exists within the chambers of the heart capable of forcing some blood flow to traverse the atrio-ventricular junction from the ventricle to the atria.
One manner of repairing this problem involves surgically implanting a prosthetic ring (i.e. xe2x80x9cannuloplasty ringxe2x80x9d) about the dilated annulus, thereby restoring the annulus to the normal size and shape and allowing the valve leaflets to function normally. Commonly, a surgeon positions the annuloplasty ring near the valve annulus and sutures the device in place.
One approach to correcting or remodeling the valve annulus has required the implantation of a rigid annuloplasty ring. Typically, an annuloplasty ring having the desired internal diameter is positioned near the heart valve and sutured in place. As a result, the diameter of the valve is reduced to the diameter of the annuloplasty ring. This procedure utilizing current annuloplasty rings has several shortcomings. For example, the tissue comprising the heart, particularly in the area of the heart valves, is flexible. The implantation of a rigid annuloplasty ring restricts the natural flexibility of this tissue, and may impact the heart""s function. Also, the diameter of the dilated annulus is substantially larger than the annuloplasty ring, thereby making the implantation surgery unnecessarily time consuming. The surgeon is required to position the prosthesis near a portion of the tissue and suture the ring in place. Thereafter, the opposing tissue is forced to engage the ring and is attached to the annuloplasty ring with sutures. Consequently, the sutures may be under different stress loads, and could result in an increased risk of ring dehiscence.
There is thus a need for a flexible annuloplasty prosthesis and implantation device which enables a surgeon to precisely position and apply an annuloplasty ring to the dilated valve annulus.
The present invention solves the aforementioned problems in that the resilient annuloplasty ring of the present invention may be stretched to the diameter of the dilated valve annulus prior to implantation, thereby simplifying the implantation process. In addition, the contractive force of the resilient annuloplasty ring of the present invention may controllably reduce the diameter of an incompetent dilated valve annulus to more competent diameter. Those skilled in the art will appreciate the present invention is easy to manufacture and may be manufactured from a plurality of materials.
The annuloplasty ring of the present invention comprises a resilient inner sizing member positioned within a flexible outer attachment sheath. The resilient inner sizing member applies a contractive force to the incompetent annulus tissue. The flexible outer attachment sheath permits the surgeon to attach the device to the annulus tissue in a plurality of manners including suturing and stapling. The annuloplasty ring of the present invention may be manufactured from a plurality of biologically compatible materials having sufficient resiliency to permit stretching during implantation and having sufficient contractive force to permit a reduction in the diameter of the incompetent valve annulus.
An alternate embodiment of the present self molding annuloplasty ring comprises an resilient inner sizing member positioned within a flexible outer attachment sheath, the ring further having a plurality of attachment members positioned thereon. The attachment members may comprise a plurality of devices, including, without limitation, needles, barbs, or hooks. In addition, the attachment members may be manufactured from a biologically compatible material such as, without limitation, stainless steel, titanium, and Nitinol.
In yet another embodiment of the present invention, a self molding annuloplasty ring having a predetermined contracted diameter is disclosed. This embodiment comprises a resilient inner sizing member positioned within a series of individual support members. A flexible outer attachment sheath is positioned on the exterior of the support members. This embodiment permits the surgeon to predetermine the inner diameter of a repaired valve annulus, thereby rendering an incompetent valve competent. Those skilled in the art will appreciate that the support members may be manufactured from a biologically compatible material such as, without limitation, plastic and elastomer.
Other objects, features, and advantages of the present invention will become apparent from a consideration of the following description of the preferred embodiments.